Starting mechanism

ABSTRACT

The output shaft of a starting mechanism is translatable by the magnetic flux of an energized actuator coil located about the shaft. The return path for this magnetic flux includes a cylinder affixed to the housing of the mechanism, an armature rotatable relative to both the shaft and housing, and a tachometer wheel driven by the shaft. The cylinder has one set of flanges that coact with a magnetic flux to pivot the armature and another set to coact with the tachometer wheel to induce a voltage in a tachometer coil as a result in changes in magnetic field through the cylinder. A pinion on the output shaft drives an idler gear that is pivoted into engagement with the starter gear of an internal combustion engine by a bracket connected to the actuator armature by a leaf spring. The actuator armature is also connected to the field switch for the starting motor by a linkage that closes the switch to start the motor when the magnetic flux aligns the armature with the flanges of the cylinder. Above a predetermined speed, a frequency detection circuit connected with the tachometer coil opens the current path through the actuator coil. When the actuator coil subsequently deenergizes, a return spring pivots the armature out of alignment with the flanges to disengage the starter gear and open the field switch.

United States Patent 1191 Sawyer et al.

[ 51 Jan. 30, 1973 [54] STARTlNG MECHANISM [75] Inventors: Elbert M.Sawyer, Torrance, Calif.;

Fred 11. Kelly, Anderson, lnd.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: April 19, 1971 [2]] Appl. No.: 134,962

[52] U.S. Cl ..290/37, 290/38 [51] Int. Cl ..F02n 11/00 [58] Field ofSearch ..290/38, 37

[56] References Cited UNITED STATES PATENTS 3,084,561 4/1963 Mattson..290/38 X 3,440,433 4/1969 Coman ..290/38 3,124,694 3/1964 Seilly..290/38 3,177,368 4/1965 Seilly ..290/38 3,223,863 12/1965 Preece et al...290/38 X 3,543,039 11/1970 Mosier ..290/38 3,062,966 11/1962 Merriam..290/38 3,399,576 9/1968 Seilly et al. ..290/38 X [57] ABSTRACT Theoutput shaft of a starting mechanism is translatable by the magneticflux of an energized actuator coil located about the shafLThe returnpath for this magnetic flux includes a cylinder affixed to the housingof the mechanism, an armature rotatable relative to both the shaft andhousing, and a tachometer wheel driven by the shaft. The cylinder hasone set of flanges that coact with a magnetic flux to pivot the armatureand another set to coact with the tachometer wheel to induce a voltagein a tachometer coil as a result in changes in magnetic field throughthe cylinder. A pinion on the output shaft drives an idler gear that ispivoted into engagement with the starter gear of an internal combustionengine by a bracket connected to the actuator armature by a leaf spring.The actuator armature is also connected to the field switch for thestarting motor by a linkage that closes the switch to start the motorwhen the magnetic flux aligns the armature with the flanges of thecylinder. Above a predetermined speed, a frequency detection circuitconnected with the tachometer coil opens the current I 8 Claims, 4Drawing Figures PAIENTEDJANBO ma 3.714.450

I XVENTORS ATTOR N EY offunctions.

The magnetic flux created by the energization of an actuator coil hasheretofore been employed in starting mechanisms to translate its outputshaft for the purpose of clutching a rotor, for engaging the startergear of an internal combustion engine, or for controlling the fieldswitch of the starting motor. In other starting mechanisms, magneticaction has been employed to rotate an idler gear driven by the outputshaft into engagement with the starter gear. Moreover, it has been thenormal practice with such magnetic action starting mechanisms to startup and shut down the starting motor by the manual control of theignition switch.

The starting mechanism of the present invention provides all of thesefunctions through the energization of a single actuator coil and theoutput provided by a tachometer coil, both such coils being woundconcentrically about the output shaft of the mechanism. When energizedthrough operation of the ignition switch of the vehicle, the actuatorcoil creates in the output shaft a magnetic flux of sufficientmagnetomotive force to lift the rotor of the motor off a brake washeragainst the action of a helical restraining spring. The return path forthe flux created by the actuator coil includes a tachometer wheelaffixed to the shaft, an actuatorv cylinder supported by the housing ofthe mechanism, and an actuator armature pivotable relative to both theshaft and the cylinder between two positions. To cause rotation of thetachometer wheel to induce a voltage in the tachometer coil, a pair ofdiametrically opposed flanges extend axially from one end of thecylinder over the teeth of the tachometer wheel. To magnetically alignthe actuator armature in one of the two positions, a second pair ofdiametrically opposed flanges extend from the other end of the cylinderover the actuator armature. The output shaft of the mechanism is meshedwith an idler gear that is pivotable into engagement with the startergear by a leaf spring connecting the actuator armature with a bracketsupporting the idler gear. When the idler gear is engaged with thestarter gear, a linkage also connected to the actuator armature, closesthe contacts of the field switch for the starting motor to commencerotation of the output shaft. When the shaft attains a predeterminedspeed, a circuit connected with the tachometer coil opens the currentpath through the actuator coil and allows the actuator to be energized.As the magnetic flux falls, the spring restraining the translation ofthe rotor slows down the rotor by urging it against the brake washer,and a second spring pivots the actuator armature out of alignment withthe flanges of the actuator cylinder, thereby pivoting the idler gearout of engagement with the starter gear and also opening the fieldswitch to the motor.

It is therefore a primary object of the present invention to provide astarting mechanism employing magnetic action to control both theengagement of an idler gear with the starter gear of an internalcombustion engine and to control the application of current to the fieldofa starting motor.

It is a further object of the present invention to provide a startingmechanism wherein the magnetic field.

provided by a first coil is employed to control the application ofcurrent to the field of the starting motor and also to induce in asecond coil an AC signal, the frequency of which is used to control theenergization of the first coil.

A first object of the present invention is to provide a startingmechanism wherein magnetic action created by the energization of a firstcoil controls the braking of the rotor of a starting motor and isinterrupted by a tachometer wheel to induce voltages in a second coiladapted to be connected with a circuit for detecting the speed of therotor.

It is a further and more specific object of the present invention toprovide a starting mechanism of the foregoing type wherein the magneticflux provided by the single actuator coil is employed to brake the rotorof a starting motor, pivot an idler gear on the output shaft of themechanism into engagement with a starter gear of an internal combustionengine, and to operate a circuit for deenergizing the coil above apredetermined speed of the shaft.

These and other objects, advantages, and details of the presentinvention will become apparent with reference to the followingdescription taken in conjunction with the drawings wherein:

FIG. 1 is a longitudinal view with parts in section of a startingmechanism constructed in accordance with the subject invention;

FIG. 2 is a view taken along line 22 in FIG. 1;

FIG. 3 is a view taken along line 33 in FIG. 1; and,

FlG.-4 is a circuit controlling the energization of the field andactuator coils of FIG. 1.

With reference now to FIG. 1, there is shown a starting motor 10 havinga rotor 12 translated by the magnetic action of an actuator coil 14 toovercome the effect of spring 16 urging rotor 12 against brake washerl8. Rotor 12 has an output shaft 20 that is drivably connected to apinion 22 rotatably supported in mesh with an idler gear 24 by an idlerhousing 26. This housing is pivotable about a hub 28 to swing idler gear24 clockwise when viewed in FIG. 3 into engagement with the startinggear 30 of an internal combustion engine.

The return path for the magnetic flux created by the energization ofactuator coil 14 includes a tachometer wheel 32 energization of actuatorcoil 14 includes a tachometer wheel 32 affixed to shaft 20, an actuatorcylinder 34 press-fitted into housing 3.6, and an actuator armature 38pivotable on the sleeve bearing 40 relative to both shaft 20 andcylinder 34. To effect such rotation, actuator armature 38 has a-pair ofdiametrically'opposed teeth 41 and 42 alignable by the mag netic actionof actuator coil 14 under flanges 43 and 44 extending axially from oneend of cylinder 34. When actuator coil 14 is deenergized, the teeth 41and 42 of armature 38 are maintained in a nonaligned position relativeto flanges 43 and 44 of cylinder 34 by a return spring 46, one end ofwhich 47 is connected to armature 38 and the other end 48 of which isconnected to cylinder 34. To allow idler gear 24 to be pivoted intoengagement with starter gear 30, idler housing 26 has an opening (notshown) spanning the width of pinion 24 and is connected to actuatorarmature 38 by a leaf spring 50 through opening 52 of housing 36.

In addition to effecting such gear engagement, the alignment of theteeth 41 and 42 with flanges 43 and 44 upon the energization of actuatorcoil 14 causes the application of current to the field winding 54 ofmotor 12. This is effected by a lost motion like 56 connecting teeth 41to field switch 58. Switch 58, as shown in FIG. 2, is located in anopening 60 of an axially extending wall 62 of drive housing 36. Lostmotion linkage 56 includes a rod 64, one end of which is slidably cammedin a curved slot 66 through tooth 41 and the other end of which isconnected to a pivoted lever 68, another part of the linkage, thatpushes armature 70 of field switch 58. Contacts 72 of switch 58 are heldin a normally open position by a spring 74, and upon the alignment ofteeth 41 and 42 with flanges 43 and 44, are closed by the linkage tocomplete the circuit for field winding 54 through switch terminals 75and 76, brushes 78, commutator bars 80 of rotor 12, brushes 82 andground 90.

As will be more fully described below with reference to the circuitshown in FIG. 4, the apparatus for detecting the speed of rotor 12includes output shaft 20 thereof having a tachometer wheel 32 drivablyconnected. For completing a path for the magnetic flux created by themagnetomotive force (i,e., ampere turns) of actuator coil 14 whenenergized, tachometer wheel 32 has a plurality of equally spaced teeth82 extending from the periphery thereof within another plurality offlanges 84 extending from the other end of actuator cylinder 34. Thevariation of magnetic flux in cylinder 34 caused by the interruption ofthe flux between teeth 82 and flanges 84 induces a voltage in atachometer coil 86 that is wound concentrically with actuator coil 14 ona bobbin 88 secured within actuator cylinder 34. To provide a suitablesliding and bearing surface for brake spring 16, a nonmagnetic springseat 89 is arranged over the hub of tachometer wheel 32 between one endof spring 16 and the axial tips of flanges 84.

OPERATION The circuit for controlling the energization of actuator coil14 and the operation of starting motor may be understood with referenceto the schematic representation of FIG. 4. As there shown, crankingposition contacts 96 of ignition switch 98 connects the positiveterminal of battery 102, both to the base of transistor 104 throughresistor 106 and to the collector of transistor 104 through actuatorcoil 14. Since the emitter of transistor 104 is grounded at 90 throughdiode 108, such closure of cranking contacts 96 turns on transistor 104to draw current through actuator coil 14. This draws teeth 41 and 42 ofactuator armature38 into alignment with flanges 43 and 44 of actuatorcylinder 34 to close contacts 72 of field switch 58 through the actionof lost motion linkage 56. Current is then applied through field coil 54to armature windings of rotor 12 through brushes 78 and 82 andcommutator bars 80.

As the speed of rotor 12 increases, the interruption of the flux pathbetween tachometer teeth 82 of wheel 32 and flanges 84 of cylinder 34varies the flux density therein, thereby inducing voltage pulses intachometer coil 86. The negative going pulses, and especially that uponthe first flux interruption or start up, are blocked by diode 110 andthe positive going pulses are applied thereby through resistor 112 to afilter comprised of capacitor 114 in parallel with resistor 116. Thevoltage developed by this filter is proportional to the change of fluxproduced in actuator cylinder 34 by tachometer wheel 32, such changebeing proportional to the speed of rotor 12.

When the rotor 12 attains a predetermined speed, the voltage developedby the filter is sufficient to enable the gate of SCR 120 throughconductor 118. Since the anode of SCR 120 is biased positively withrespect to the cathode from battery 102 through cranking contact 96, theenabling voltage on conductor 118 renders SCR 120 conductive, therebygrounding the base of transistor 104 and rendering transistor 104nonconductive. This opens the current path through actuator coil 14 andallows the return of actuator armature 38 and the opening of fieldcontacts 72, as has been hereinabove described. Diode 108, connected tothe emitter of transistor 104 in this circuit, assures that the voltageat the base of transistor 104 when conductive is slightly. above ground90, thereby assuring a forward anode to cathode bias on SCR 120. Diode123 connected across actuator coil 14 allows the energy therein todissipate upon deenergization rather than develop voltage transientsthat could damage transistor 104.

The circuit shown in FIG. 4 also assures that actuator coil 14 and inturn starting motor 10 are not inadvertently activated during normalrunning of the engine. Such protection is provided through a circuitcoupled to the gate of SCR 120 and energized from battery 102 throughrunning contacts of ignition switch 98 and an oil indicator lamp 122.Upon initial closure of ignition switch 98, the path from battery 102 iscompleted to ground 90 through running contacts 100, oil indicator lamp122, and the normally closed contacts of an oil pressure switch 124. Theincrease in oil pressure caused when cranking or running the engineopens the oil pressure switch 124 to provide an otherwise groundedenabling voltage to the gate of SCR 120 from battery 102 through lamp122, resistor 126, and diode 128. Diode blocks any leakage through thispath from battery 102 to ground 90. Should the cranking contacts 96 ofignition switch 98 be inadvertently closed thereafter, SCR would berendered conductive to prevent conduction through transistor 104 andtherefore both energization of actuator coil 14 and in turn activationof the starting motor 10.

Since, before attaining self-sustaining operation, the engine maydevelop sufficient oil pressure to open oil pressure switch 124, meansmust be provided to allow continued energization of coil 14, and thecranking resulting therefrom, for some period after the closure ofcranking contact 96. Thus, means must be provided to prevent the voltagethat would otherwise be grounded through the contacts of oil pressureswitch 124 from enabling the gate of SCR 120 through resistor 126 anddiode 128 for some period after the closure of cranking contacts 96. Toeffect such operation, a transistor 130 having its collector connectedbetween resistor 126 and the anode of diode 128 and its emitterconnected to ground 90 is rendered conductive to ground the enablingvoltage shortly after the closure of cranking contacts 96 and prior tothe opening of oil switch contact 124. However, since conduction throughtransistor 130 promptly upon closure of cranking contacts 96 woulddefeat the above-described protection against inadvertent starting motorcranking with the engine running, conduction through transistor 130 isdelayed for a period depending on charging characteristics of capacitor132 and a breakdown voltage of a Zener diode 134 connected with the baseof transistor 130, as shown. Thus, capacitor 132 charges from battery102 through the closed cranking contact 96 and a resistor 136 untilZener 134 breaks down to provide a bias across resistor 138 renderingtransistor 130 conductive.

Oil pressure switch 124, transistor 130, Zener 134, and capacitor 132thus cooperate first to lock out attempted energization of coil 14 withthe engine running; secondly, to permit such lockout for only a shortperiod after the commencement of such attempted energization with theengine running; and thirdly, to prevent such energization with theengine running after the short period in order to permit the engine tobe started in the first place. The period of lockout is selected on onehand to be longer than the period of any inadvertent or accidentalclosure of the cranking contacts 96 but substantially shorter on theother hand than the shortest contemplated period required for enginestarting.

As a further protective feature, possible damage to the internal geartrain by attempted re-engagement with the rotor 12 not stopped isprovided promptly upon the deenergization of actuator coil 14 throughthe action of spring 16 urging rotor 12 against break washer 18. Thus,rotor 12 would be braked after the opening of cranking contacts 96 uponan apparent engine start, and damage would be avoided upon subsequentclosure of contact 96 to reinstitute cranking when the non-startcondition becomes apparent.

Having described one embodiment of the present invention, it isunderstood that the specific terms and examples are employed in adescriptive sense only and not for the purposes of limitation. Otherembodiments of the invention, modifications thereof, and alternativesthereto may be used. We therefore aim in the appended claims to coversuch modifications and changes as fall within the true spirit of myinvention.

What we claim is new and desire to secure by Letters Patent of theUnited States is:

1. In a starting mechanism having a translatable output shaft, means fordetecting the speed of said shaft and translating said shaft comprisingin combination:

a. a first magnetically susceptible member supported about said shaftand comprising a flange;

b. first coil means electrically energizable to establish a magneticflux in said shaft for translating said shaft;

c. a. second magnetically susceptible member rotatable with said shaftin proximity to said flange of said first member, whereby with saidfirst coil means energized a magnetic flux path is provided through saidfirst and second members and said shaft and whereby the density of saidmagnetic flux between said second member and said flange varies with therotation of said second member relative to said first member; and

d. second coil means operative to develop signals of magnitude andfrequency varying with said said flux density, whereby said signalsrepresent the speed of said shaft.

2. In a starting mechanism having a shaft, a housing rotatablysupporting said shaft, and a housing part rotatable about said shaft,means for detecting the speed of said shaft and rotating said housingpart thereabout comprising in combination:

a. a first magnetically susceptible member supported by said housingabout said shaft and comprising a flange;

. first coil means electrically energizable to establish a magnetic fluxin said shaft;

c. a second magnetically susceptible member rotatable with said shaft inproximity to said flange of said first member, whereby with said firstcoil means energized a magnetic flux path is provided through said firstand second members and said shaft and whereby the density of saidmagnetic flux between said second member and said flange varies with therotation of said second member relative to said first member;

. second coil means operative to develop signals of magnitude andfrequency varying with said change in said flux density, whereby saidsignals represent the speed of said shaft;

e. a third magnetically susceptible member having a tooth displaceablebetween aligned and nonaligned positions relative to a second flange ofsaid first member, whereby said first, second, and third members andsaid shaft provide a path for said magnetic field created by saidenergization of said first coil means; and

f. means connecting said third member and said housing part, wherebysaid third member rotates said housing part about said shaft when saidfirst coil means are energized and said tooth of said third memberrotates from said nonaligned to said aligned positions.

3. In a starting mechanism having a shaft, a housing rotatablysupporting said shaft, and a housing part rotatable about said shaft,means for detecting the speed of said shaft and rotating said housingpart thereabout comprising in combination:

a. a first magnetically susceptible member supported by said housingabout said shaft and comprising a flange;

b. first coil means electrically energizable to establish a magneticflux in said shaft;

0. a second magnetically susceptible member rotatable with said shaft inproximity to said flange of said first member, whereby with said firstcoil means energized a magneticflux path is provided though said firstand second members and said shaft and whereby the density of saidmagnetic flux between said second member and said flange varies with therotation of said second member relative to said first member;

. second coil means operative to develop signals of magnitude andfrequency varying with said change in said flux density, whereby saidsignals represent the speed of said shaft;

e. a third magnetically susceptible member rotatable relative to saidshaft and said first member, said third member having a tooth in aposition of alignment with a second flange of said first member whensaid first coil means are energized and in a position of non-alignmentwhen said first coil means are deenergized, whereby said first, secondand third member and said shaft provide a path for magnetic flux createdby the energization of said first coil means;

f. first and second drive means, said first drive means drivablyconnected with said shaft and said second drive means drivably connectedwith said first drive means and supported by said housing part; and

g. resilient means connecting said second member and said housing part,whereby rotation of said I third member to one of said aligned andnonaligned positions rotates said second drive means about said firstdrive means.

4. In a starting mechanism having a shaft, a housing rotatablysupporting said shaft, and a housing part rotatable about said shaft,means for detecting the speed of said shaft and rotating said housingpart thereabout comprising in combination:

a. a first magnetically susceptible member supported by said housingabout said shaft and comprising a flange; I

b. first coil means supported electrically energizable to establish amagnetic flux in said shaft;

c. a second magnetically susceptible member rotatable with said shaft inproximity to said flange of said first member, whereby said first coilmeans energized a magnetic flux path is provided through said first andsecond members and said shaft and whereby the density of said magneticflux between said second member and said flange varies with the rotationof said second member relative to said first member;

. a third magnetically susceptible member rotatable relative to saidshaft and to said first member, said third member having a toothdisplaceable between an aligned and a non-aligned position relative to asecond flange of said first member, whereby said first, second and thirdmembers and said shaft provide a path for said magnetic field created bysaid energization of said first coil means;

f. means connecting said third member and said housing part, wherebysaid third member rotates said housing part when said first coil meansare energized and said tooth of said third member is in one of saidaligned and non-aligned positions with respect to said second flange ofsaid first member; and

g. second resilient means connecting said first and second members andoperative when said coil means are deenergized to return said secondmember into said position of non-alignment with respect to said firstmember.

5. In a starting mechanism having an output shaft, first, second, andthird normally non-conductive switches each having an input and anoutput electrode, a normally conductive switch responsive to and openedby the presence of a predetermined external condition, said normallyconductive switch being connected with said output electrode of saidfirst normally non-conductive switch, a battery having a first terminalconnected to a point of constant reference potential and a secondterminal connected to said input electrode of said first, second, andthird normally non-conductive switches, an improved circuit forcontrolling said mechanism comprising:

a. a first magnetically susceptible member displaceable relative to saidthird normally non conductive switch and operable when displacedrelative thereto to switch said third switch between a conductive stateand a non-conductive state;

b. a second magnetically susceptible member for providing magnetic fluxto said first member to displace said first member relative to saidthird switch;

. a third magnetically susceptible member operable to change saidmagnetic flux in said second member in response to the speed of saidshaft, whereby said change in flux in said second member varies withsaid speed;

. a first transistor having an output electrode connected to said pointof constant reference potential and a control electrode connected tosaid output electrode of said second switch;

. a second transistor having an input electrode connected to said outputelectrode of said first switch, an output electrode connected to saidpoint of constant reference potential, and a control electrode connectedto said output electrode of said second switch;

f. first coil means for creating said magnetic flux, said first coilmeans having one end thereof connected to said output electrode of saidsecond switch and the other end thereof connected to said inputelectrode of said first transistor, whereby, when said second switch isrendered conductive, said first transistor is rendered conductive toenergize said first coil means and whereby said flux displaces saidfirst member relative to said second member to render said third switchconductive;

. a controllable unidirectional current conducting device having ananode connected with said output electrode of said second switch, acathode connected with said point of constant reference potential, and acontrol electrode connected with said output electrode of said firstswitch, said device being rendered conductive upon the application of apredetermined voltage to the control electrode thereof, whereby whensaid device is conductive, said first transistor is renderednon-conductive to deenergize said first coil means, thereby allowingsaid first magnetically susceptible member to be displaced relative tosaid second magnetically susceptible member to render said third switchnon-conductive; and

h. second coil means responsive to said change in magnetic flux effectedin said second magnetically susceptible member, one end of said secondcoil means being connected to said point of constant reference potentialand the other end connected to said control electrode of saidcontrollable unidirectional current conducting device, whereby when saidshaft exceeds a predetermined speed, said second coil means produce saidpredetermined voltage.

6. ln astarting mechanism having an output shaft, first, second, andthird normally non-conductive switches each having an input and anoutput electrode, a normally conductive switch responsive to and openedby the presence of a predetermined external condition, said normallyconductive switch being connected with said output electrode of saidfirst normally non-consecond terminal connected to said input electrodeof said first, second, and third normally non-conductive switches, animproved circuit for controlling said mechanism comprising:

a. a first magnetically susceptible member displaceable relative to saidthird normally non-conductive switch and operable when displacedrelative thereto to switch said third switch between a conductive stateand a non-conductive state;

b. a second magnetically susceptible member for providing magnetic fluxto said first member to displace said first member relative to saidthird switch;

c. a third magnetically susceptible member operable to change saidmagnetic flux in said second member in response to the speed of saidshaft, whereby said change in flux in said second member varies withsaid speed;

d. a first transistor having an output electrode connected to said pointof constant reference potential and a control electrode connected tosaid output electrode of said second switch;

e. a second transistor having an input electrode connected to saidoutput electrode of said first switch, an output electrode connected tosaid point of constant reference potential, and a control electrodeconnected to said output electrode of said second switch;

f. first coil means for creating said magnetic flux, said first coilmeans having one end thereof connected to said output electrode of saidsecond switch and the other end thereof connected to said inputelectrode of said first transistor, whereby, when said second switch isrendered conductive, said first transistor is rendered conductive toenergize said first coil means and whereby said flux displaces saidfirst member relative to said second member to render said third switchconductive;

g. a controllable unidirectional current conducting device having ananode connected with said output electrode of said second switch, acathode connected with said point of constant reference potential, and acontrol electrode connected with said output electrode of said firstswitch, said device being rendered conductive upon the application of apredetermined voltage to the control electrode thereof, whereby whensaid device is conductive, said first transistor is renderednon-conductive to deenergize said first coil means, thereby allowingsaid first magnetically susceptible member to be displaced relative tosaid second magnetically susceptible member to render said third switchnon-conductive;

h. second coil means responsive to said change in magnetic flux effectedin said second magnetically susceptible member, one end of said secondcoil means being connected to said point of constant reference potentialand the other end connected to said control electrode of saidcontrollable unidirectional current conducting device, whereby when saidshaft exceeds a predetermined speed, said second coil means produce saidpredetermined voltage; and

i. a unidirectional current conducting device having an anode connectedto said input electrode of said second transistor and a cathodeconnected to said control electrode of said controllable unidirectionalcurrent conducting device, whereby with said first and second switchesconductive, said controllable unidirectional current conducting devicemay be rendered conductive with one of said predetermined voltage andconduction through said second switch after said normally conductiveswitch is rendered non-conductive.

7. In a starting mechanism having a translatable output shaft, means fordetecting the speed of said shaft and for operating a brake bytranslating said shaft comprising in combination:

a. a first magnetically susceptible member supported about said shaftand comprising a flange;

b. first coil means electrically energizable to establish a magneticflux in said shaft for translating said shaft and operating said brake;

c. a second magnetically susceptible member rotatable with said shaft inproximity to said flange of said first member, whereby with said firstcoil means energized a magnetic flux path is provided through said firstand second members and said shaft and whereby the density of saidmagnetic flux between said second member and said flange varies with therotation of said second member relaengine comprising:

a. an electric cranking motor having an output shaft,

a rotor mounted on said shaft, and a stator electrically energizable torotate said rotor;

b. an actuator winding telescoped over said shaft and effective whenenergized to provide a magnetic field having a flux path linking saidshaft;

c. a toothed wheel rotatable with said shaft and forming a part of the'magnetic circuit encircling said actuator winding, whereby analternating component of magnetic flux is developed in accordance withthe shaft rotational velocity;

d. a pickup winding encircling the flux path of said alternatingcomponent;

e. circuit means responsive to the emf of said actuator winding andeffective to interrupt the current supplied thereto when said emfreaches a predetermined frequency;

an actuator cylinder supported about said shaft and comprising a flange,said actuator member forming a part of the flux path of said actuatorcoil;

g. an armature member forming a part of the flux path of said actuatorwinding and circumferentially rotatable about said shaft between alignedand non-aligned positions relative to said flange when said actuatorwinding is respectively energized and de-energized;

h. spring means biasing said armature member towards said non-alignedposition; and

i. switch means responsive to the motion of said armature member to saidaligned position defining an energizing circuit to the cranking motor.

1. In a starting mechanism having a translatable output shaft, means fordetecting the speed of said shaft and translating said shaft comprisingin combination: a. a first magnetically susceptible member supportedabout said shaft and comprising a flange; b. first coil meanselectrically energizable to establish a magnetic flux in said shaft fortranslating said shaft; c. a second magnetically susceptible memberrotatable with said shaft in proximity to said flange of said firstmember, whereby with said first coil means energized a magnetic fluxpath is provided through said first and second members and said shaftand whereby the density of said magnetic flux between said second memberand said flange varies with the rotation of said second member relativeto said first member; and d. second coil means operative to developsignals of magnitude and frequency varying with said said flux density,whereby said signals represent the speed of said shaft.
 1. In a startingmechanism having a translatable output shaft, means for detecting thespeed of said shaft and translating said shaft comprising incombination: a. a first magnetically susceptible member supported aboutsaid shaft and comprising a flange; b. first coil means electricallyenergizable to establish a magnetic flux in said shaft for translatingsaid shaft; c. a second magnetically susceptible member rotatable withsaid shaft in proximity to said flange of said first member, wherebywith said first coil means energized a magnetic flux path is providedthrough said first and second members and said shaft and whereby thedensity of said magnetic flux between said second member and said flangevaries with the rotation of said second member relative to said firstmember; and d. second coil means operative to develop signals ofmagnitude and frequency varying with said said flux density, wherebysaid signals represent the speed of said shaft.
 2. In a startingmechanism having a shaft, a housing rotatably supporting said shaft, anda housing part rotatable about said shaft, means for detecting the speedof said shaft and rotating said housing part thereabout comprising incombination: a. a first magnetically susceptible member supported bysaid housing about said shaft and comprising a flange; b. first coilmeans electrically energizable to establish a magnetic flux in saidshaft; c. a second magnetically susceptible member rotatable with saidshaft in proximity to said flange of said first member, whereby withsaid first coil means energized a magnetic flux path is provided throughsaid first and second members and said shaft and whereby the density ofsaid magnetic flux between said second member and said flange varieswith the rotation of said second member relative to said first member;d. second coil means operative to develop signals of magnitude andfrequency varying with said change in said flux density, whereby saidsignals represent the speed of said shaft; e. a third magneticallysusceptible member having a tooth displaceable between aligned andnon-aligned positions relative to a second flange of said first member,whereby said first, second, and third members and said shaft provide apath for said magnetic field created by said energization of said firstcoil means; and f. means connecting said third member and said housingpart, whereby said third member rotates said housing part about saidshaft when said first coil means are energized and said tooth of saidthird member rotates from said nonaligned to said aligned positions. 3.In a starting mechanism having a shaft, a housing rotatably supportingsaid shaft, and a housing part rotatable about said shaft, means fordetecting the speed of said shaft and rotating said housing partthereabout comprising in combination: a. a first magneticallysusceptible member supported by said housing about said shaft andcomprising a flange; b. first coil means electrically energizable toestablish a magnetic flux in said shaft; c. a second magneticallysusceptible member rotatable with said shaft in proximity to said flangeof said first member, whereby with said first coil means energized amagnetic flux path is provided though said first and second members andsaid shaft and whereby the density of said magnetic flux between saidsecond member and said flange varies with the rotation of said secondmember relative to said first member; d. second coil means operative todevelop signals of magnitude and frequency varying with said change insaid flux density, whereby said signals represent the speed of saidshaft; e. a third magnetically susceptible member rotatable relative tosaid shaft and said first member, said third member having a tooth in aposition of alignment with a second flange of said first member whensaid first coil means are energized and in a position of non-alignmentwhen said first coil means are deenergized, whereby said first, secondand third member and said shaft provide a path for magnetic flux createdby the energization of said first coil means; f. first and second drivemeans, said first drive means drivably connected with said shaft andsaid second drive means drivably connected with said first drive meansand supported by said housing part; and g. resilient means connectingsaid second member and said housing part, whereby rotation of said thirdmember to one of said aligned and non-aligned positions rotates saidsecond drive means about said first drive means.
 4. In a startingmechanism having a shaft, a housing rotatably supporting said shaft, anda housing part rotatable about said shaft, means for detecting the speedof said shaft and rotating said housing part thereabout comprising incombination: a. a first magnetically susceptible member supported bysaid housing about said shaft and comprising a flange; b. first coilmeans supported electrically energizable to establish a magnetic flux insaid shaft; c. a second magnetically susceptible member rotatable withsaid shaft in proximity to said flange of said first member, wherebysaid first coil means energized a magnetic flux path is provided throughsaid first and second members and said shaft and whereby the density ofsaid magnetic flux between said second member and said flange varieswith the rotation of said second member relative to said first member;d. a third magnetically susceptible member rotatable relative to saidshaft and to said first member, said third member having a toothdisplaceable between an aligned and a non-aligned position relative to asecond flange of said first member, whereby said first, second and thirdmembers and said shaft provide a path for said magnetic field created bysaid energization of said first coil means; f. means connecting saidthird member and said housing part, whereby said third member rotatessaid housing part when said first coil means are energized and saidtooth of said third member is in one of said aligned and non-alignedpositions with respect to said second flange of said first member; andg. second resilient means connecting said first and second members andoperative when saiD coil means are deenergized to return said secondmember into said position of non-alignment with respect to said firstmember.
 5. In a starting mechanism having an output shaft, first,second, and third normally non-conductive switches each having an inputand an output electrode, a normally conductive switch responsive to andopened by the presence of a predetermined external condition, saidnormally conductive switch being connected with said output electrode ofsaid first normally non-conductive switch, a battery having a firstterminal connected to a point of constant reference potential and asecond terminal connected to said input electrode of said first, second,and third normally non-conductive switches, an improved circuit forcontrolling said mechanism comprising: a. a first magneticallysusceptible member displaceable relative to said third normallynon-conductive switch and operable when displaced relative thereto toswitch said third switch between a conductive state and a non-conductivestate; b. a second magnetically susceptible member for providingmagnetic flux to said first member to displace said first memberrelative to said third switch; c. a third magnetically susceptiblemember operable to change said magnetic flux in said second member inresponse to the speed of said shaft, whereby said change in flux in saidsecond member varies with said speed; d. a first transistor having anoutput electrode connected to said point of constant reference potentialand a control electrode connected to said output electrode of saidsecond switch; e. a second transistor having an input electrodeconnected to said output electrode of said first switch, an outputelectrode connected to said point of constant reference potential, and acontrol electrode connected to said output electrode of said secondswitch; f. first coil means for creating said magnetic flux, said firstcoil means having one end thereof connected to said output electrode ofsaid second switch and the other end thereof connected to said inputelectrode of said first transistor, whereby, when said second switch isrendered conductive, said first transistor is rendered conductive toenergize said first coil means and whereby said flux displaces saidfirst member relative to said second member to render said third switchconductive; g. a controllable unidirectional current conducting devicehaving an anode connected with said output electrode of said secondswitch, a cathode connected with said point of constant referencepotential, and a control electrode connected with said output electrodeof said first switch, said device being rendered conductive upon theapplication of a predetermined voltage to the control electrode thereof,whereby when said device is conductive, said first transistor isrendered non-conductive to deenergize said first coil means, therebyallowing said first magnetically susceptible member to be displacedrelative to said second magnetically susceptible member to render saidthird switch non-conductive; and h. second coil means responsive to saidchange in magnetic flux effected in said second magnetically susceptiblemember, one end of said second coil means being connected to said pointof constant reference potential and the other end connected to saidcontrol electrode of said controllable unidirectional current conductingdevice, whereby when said shaft exceeds a predetermined speed, saidsecond coil means produce said predetermined voltage.
 6. In a startingmechanism having an output shaft, first, second, and third normallynon-conductive switches each having an input and an output electrode, anormally conductive switch responsive to and opened by the presence of apredetermined external condition, said normally conductive switch beingconnected with said output electrode of said first normallynon-conductive switch, a battery having a first terminal connected to apoint of constant reference potential and a second termInal connected tosaid input electrode of said first, second, and third normallynon-conductive switches, an improved circuit for controlling saidmechanism comprising: a. a first magnetically susceptible memberdisplaceable relative to said third normally non-conductive switch andoperable when displaced relative thereto to switch said third switchbetween a conductive state and a non-conductive state; b. a secondmagnetically susceptible member for providing magnetic flux to saidfirst member to displace said first member relative to said thirdswitch; c. a third magnetically susceptible member operable to changesaid magnetic flux in said second member in response to the speed ofsaid shaft, whereby said change in flux in said second member varieswith said speed; d. a first transistor having an output electrodeconnected to said point of constant reference potential and a controlelectrode connected to said output electrode of said second switch; e. asecond transistor having an input electrode connected to said outputelectrode of said first switch, an output electrode connected to saidpoint of constant reference potential, and a control electrode connectedto said output electrode of said second switch; f. first coil means forcreating said magnetic flux, said first coil means having one endthereof connected to said output electrode of said second switch and theother end thereof connected to said input electrode of said firsttransistor, whereby, when said second switch is rendered conductive,said first transistor is rendered conductive to energize said first coilmeans and whereby said flux displaces said first member relative to saidsecond member to render said third switch conductive; g. a controllableunidirectional current conducting device having an anode connected withsaid output electrode of said second switch, a cathode connected withsaid point of constant reference potential, and a control electrodeconnected with said output electrode of said first switch, said devicebeing rendered conductive upon the application of a predeterminedvoltage to the control electrode thereof, whereby when said device isconductive, said first transistor is rendered non-conductive todeenergize said first coil means, thereby allowing said firstmagnetically susceptible member to be displaced relative to said secondmagnetically susceptible member to render said third switchnon-conductive; h. second coil means responsive to said change inmagnetic flux effected in said second magnetically susceptible member,one end of said second coil means being connected to said point ofconstant reference potential and the other end connected to said controlelectrode of said controllable unidirectional current conducting device,whereby when said shaft exceeds a predetermined speed, said second coilmeans produce said predetermined voltage; and i. a unidirectionalcurrent conducting device having an anode connected to said inputelectrode of said second transistor and a cathode connected to saidcontrol electrode of said controllable unidirectional current conductingdevice, whereby with said first and second switches conductive, saidcontrollable unidirectional current conducting device may be renderedconductive with one of said predetermined voltage and conduction throughsaid second switch after said normally conductive switch is renderednon-conductive.
 7. In a starting mechanism having a translatable outputshaft, means for detecting the speed of said shaft and for operating abrake by translating said shaft comprising in combination: a. a firstmagnetically susceptible member supported about said shaft andcomprising a flange; b. first coil means electrically energizable toestablish a magnetic flux in said shaft for translating said shaft andoperating said brake; c. a second magnetically susceptible memberrotatable with said shaft in proximity to said flange of said firstmember, whereby with said first Coil means energized a magnetic fluxpath is provided through said first and second members and said shaftand whereby the density of said magnetic flux between said second memberand said flange varies with the rotation of said second member relativeto said first member; and d. second coil means operative to developsignals of magnitude and frequency varying with said change in fluxdensity, whereby said signals represent the speed of said shaft.